The present application relates to a method for the manufacture of a cooling module and to a corresponding cooling module for a battery module composed of one or more cells, in particular having accumulators, in particular lithium ion cells, which are used for the formation of a traction battery and/or a traction battery module for vehicles having an electric drive chain. Such battery modules can, for example, be used in electric vehicles, hybrid vehicles with combustion engines or hybrid vehicles with fuel cells. Through the modular assembly of a battery module in accordance with the invention this can also be used for different purposes, for example, for stationary applications or small traction applications, such as e.g. in a wheelchair.
In the published PCT application of Akasol Engineering GmbH, Publication No. WO2010121832 A1, a cooling module for a battery module composed of a plurality of cells, in particular with accumulators, in particular lithium ion cells, is described which are used for the formation of a traction battery and/or a traction battery module for vehicles having an electric drive chain.
A battery module system which is assembled from a plurality of like battery modules can, for example, be designed in order to cover a power range having a content of energy of between 1 kWh and 400 kWh or more. When, for example, a battery module system is designed for a continuous power of 20 kW, peak powers of, for example, 100 kW can still be required from the battery for acceleration purposes on a short term basis, whereby excellent acceleration values can be achieved. One can work with a charging power of 40 kW, for example, during charging operations.
The above stated values are purely exemplary, however, on the other hand, represent values which can generally be achieved with commercially available lithium ion batteries.
The cooling module in accordance with the above mentioned PCT application should be of compact design and be thermically optimized and, in particular be configured so that the operating temperature of the battery module and/or the battery module system can be maintained within narrow boundaries in order to, if possible, avoid the local overheating of individual cells, increased temperatures of one or more cells, or the operation at too low a cell temperature.
In order to satisfy this object, a cooling module for a battery module composed of a plurality of cells is provided in the mentioned PCT application which is characterized in that the cooling module has cooling plates at at least first and second oppositely disposed sides and is provided with heat conducting connection plates extending between these two sides which form compartments for receiving the cells therebetween, wherein the cooling module is preferably approximately of the shape of a parallelepiped.
In the likewise published German patent application of the Akasol Engineering GmbH, Publication No. DE 10 2009 018 787 A1, a method for the manufacture of a cooling module for a rechargeable battery is provided, wherein the cooling module is approximately of the shape of a parallelepiped and has a liquid cooling at at least three consecutive sides, wherein an approximately rectangular sheet metal plate or an approximately rectangular region of a sheet metal strip is pressed in order to form a groove-like inlet region and a groove-like outlet region at two oppositely disposed sides of the rectangle, as well as forming a plurality of grooves extending at least substantially parallel to one another between the inlet region and the outlet region. The rectangular shaped plate and/or the rectangular shaped region of the strip is subsequently bent at at least two positions in order to form two substantially rectangular corners.
Such a method can be easily reproduced in a production plant in a cost-effective manner and indeed with very little material loss, whereby a series production of cooling modules is possible economically in large numbers. Through the use of sheet metal and/or aluminium or an aluminium alloy as a starting material, a relatively stiff structure can be generated with relatively thin sheet metal, for example having a thickness of approximately 1 mm, since the ribs not only serve for the cooling, but also for the stiffening. Furthermore, the thin-walled design leads to a light weight cooling module. The use of aluminium sheet metal promotes the reduction of weight.
The operating temperature of the individual battery cells should, however, not exceed a working range of e.g. 18° to 25° C., as otherwise the lifetime of the individual battery cells of a battery module can be drastically reduced in part. Due to the fact that in previous cooling modules the cooling sheet metal parts where typically subsequently provided with coolant circuits in order to realize the cooling of the battery cells, problems with regard to cooling can arise since the thermal transfer of the coolant cannot always be sufficiently ensured.